Distribution-type fuel injection pump

ABSTRACT

A fuel injection pump comprising a pump body with a compression plunger reciprocating by said camshaft to control a discharge amount and a distributor body with a distribution plunger having an outlet port communicating to an injection valve, these being separably connected to form a pump chamber between the distributor body and the compression plunger and an oil chamber communicating to a fuel pump and a pump chamber between the distributor body and the pump body, and an extension of the distribution plunger and the camshaft are connected means for transmitting a definite ratio of rotation.

O Umted States Patent 1 13,ss2,240

[72] Inventor Masaaki Hokari [56] References Cited "iki-gun-Saiwma-ken, J p UNITED STATES PATENTS P 810,477 2,243,861 6/1941 Hautzehroeder ..123/139.11(B) [22] FliCd Mar. 26,1969

[45] Patented June 1, 1971 FOREIGN PATENTS [73] Assignee Diesel Kiki Kabrishiki Kaisha 1,017,519 9/1952 France 123/139.l1(B) I Tokyo Japan Primary Examiner-Robert M. Walker Pnomy 1968 Attorney-Larson, Taylor & Hinds [33] Japan ABSTRACT: A fuel injection pump comprising a pump body with a compression plunger reciprocating by said camshaft to control a discharge amount and a distributor body with a distribution plunger having an outlet port communicating to an [54] Y J F SF FUEL INJECTION PUMP injection valve, these being separably connected to form a nuns pump chamber between the distributor body and the compres- [52] US. Cl... 417/485 sion plunger and an oil chamber communicating to a fuel [51] Int. Cl F04b 13/02 pump and a pump chamber between the distributor body and [50] Field of Search 103/2.1, 2, the pump body, and an extension of the distribution plunger 154,411,412, 227;230/225, 139.11 B; 123/139.l1;4l7/485 and the camshaft are connected means fortransmitting a definite ratio of rotation.

PATENTEUJUN nan 3,582,240

' saw 3 BF 3 I FIG.3

DISTRIBUTION TYPE FUEL INJECTION PUMP This invention relates to a distribution type fuel injection pump of novel construction which feeds a fuel compressed by a plunger reciprocating by a camshaft and distributes it to each cylinder of a multicylinder engine by means of a distribution plunger turned by and provided in parallel .with said camshaft.

In conventional distribution-type fuel injection pumps it has been usual to assemble and incorporate a fuel compression plunger and a distribution plunger in a body or to incorporate a compression plunger and a distribution plunger, though separately provided, in a same pump body. When either one of the plungers became disused the described construction however made it unavoidable to waste unused plunger or pump and this resulted in a great uneconomy. Another inconvenience of the conventional construction is that the distribution and compression parts are inseparably provided in one casing so that in almost all cases the damage or loss in any one of the assembled parts lead to a damage or loss in other parts and cause troubles in servicing. In the known fuel injection pumps there are still other disadvantages that in the beginning of suction stroke of a compression plunger fuel feeding cannot be made as desired in a pump chamber so that negative pressure may be generated without giving a stable discharge amount. To overcome these disadvantages there have been attempted a variety of improvements in construction of the fuel injection pumps.

This invention has for its object to provide a distributiontype fuel injection pump having excellent functions for solving the problems by the construction as later described.

According to the invention, a compression plunger is provided in a barrel which is separable from a pump body asseen in an ordinary'row type fuel injection pump, a distribution plunger is incorporated in a separate distributor body with passagewaysfor fuel inlet and outlet and discharge ports connected to the injection valve and these two bodies are separably connected to an oil chamber provided therebetween so that it is possible to obtain a desired distribution type injection pump, simple in construction and easy for maintenance and repair, all the disadvantages as hereinbefore described having been removed.

In order that this invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 is a vertical sectional view of a first embodiment of a distribution type fuel injection pump according to this invention,

FIG. 2 is a sectional view on the line 11-11 of FIG. I,

Flg. 3 is a development showing relation of the opening and the closing of suction port, outlet port and discharge port relative to rotary angles of a camshaft during reciprocating strokes of a pressure feed plunger of the fuel injection pump of FIG. 1 and FIG. 4 is a vertical sectional view similar to FIG. 1 of a second embodiment of the pump according to this invention.

The invention will now be described in detail on a first embodiment used for a four cylinder engine shown in FIGS. 1 and 2. 1 shows a camshaft driven at half a rotational speed of an engine from a drive shaft of the engine not shown. 2 shows a cam integrated with the camshaft 1 and having projections same in number as that of a cylinder of the engine. 3 shows a fuel compression plunger to reciprocate in a barrel 30 by rotation of the cam 2 through a tapet 4. These are incorporated in a pump body 5 as in the row type pump. The compression plunger 3 is turned by a control rod 3b so that the amount of fuel injection is adjusted. 5a shows a distributor body having a distribution plunger 6 incorporated therein, the lower end of which is fitted to a bore on the upper part of the body 5 oiltightly by an O-ring 5b and the lower surface 5c of which is oiltightly adhered on the upper surface of the barrel 30, forming .a pump chamber 16 between the compression plunger and secured to the body 5 by means of four bolts 5d and a holding plate 5e. Between the lower surface 50 and the body 5 there is formed an oil chamber 13 enclosing the barrel 3a and connected to a fuel feed pump not shown. The distribution plunger 6 fits oiltightly and rotatably to a bore parallel with the camshaft 1 of the distributor body 5a. Thus the axial sliding of the distribution plunger is limited by engagement of a stepped portion 6a of an extension of the distribution plunger with an end surface of the bore and by engagement of an extension 6b with a stopper bolt provided coaxially. The distribution plunger 6 is turned by the camshaft l at'the same speed of the camshaft I by connection of a gearll on the extension 6b with a gear 9 on the camshaft through an intermediate gear 10 carried on the pump body. The distribution plunger 6 is provided with a circumferential groove 7 in agreement with an axis of the compression plunger 3. On the left and right sides of the groove 7 are provided longitudinal grooves 7a, 7b symmetrically in branched form and at right angles to the groove 7. Said circumferential groove 7 communicates to a pump chamber 16 on the upper end of the plunger through an outlet 17 in the center of the distributor body 5a. Said longitudinal grooves 7a, 7b in due order communicate to the outlet port 17a in the number of the engine cylinders and opening toward the upper surface of the body 5a by rotation of the distributor plunger 6. The outlet bore 17a communicates to each of the fuel injection valves of the engine not shown through an outlet port 21 of a pipe joint 5f screwed with the upper surface of the distribution body. Two more circumferential grooves 15a, 15b are provided at the both sides of the circumferential groove 7 of the distribution plunger 6. From these circumferential grooves to the sides of the circumferential groove 7 are respectively branched off four longitudinal grooves 8a, 8b for suction in such manner that these are provided at equal intervals on the circumference on each side and each pair on both sides are situated on the same line in a axial direction. The circumferential grooves 15a, 15b always communicate to the suction passages 14a, 14b on the distributor body So and are opened to the oil chamber 13 of the body 5. By rotation of the distribution plunger 6 the longitudinal grooves 8a, 8b on said same linesequentially communicate in a pair to the suction bores 12a, 12b in the distributor body 5a which are respectively communicated to the pump chamber 16. Inside the outlet port 21 of the pipe joint 5f is provided a known feed valve. A bore 18 in the radial direction of the barrel 3a provided, by cooperation with a notch 30 for controlling a fuel injection amount of the compression plunger 3, to overflow the fuel from inside the pump chamber 16, completes discharge in the course of a discharge stroke or cam lift head and varies the period of overflow by rotation of the compression plunger 3 to thereby control the amount of fuel injection. Operation of the fuel injection pump according to this invention having the construction heretofore described will now be given below. By rotation of the camshaft l the compression plunger 3 enters a discharge stroke whereupon one of the longitudinal grooves 7a, 7b for discharge in the distribution plunger 6 communicates to one of the outlet bore 17a and communicates the outlet port 21 to the pump chamber 16. Accordingly, the upper end surface of the compression plunger 3 closes the bore 18 so that the fuel is fed in compression to the injection valve of the engine through the outlet port 21 described above and thus the injection of fuel is carried out. This injection of fuel continues until a bore 18 is opened by the notch 3c of the compression plunger 3 and thereby the pump chamber 16 and the oil chamber 13 are communicated through. By further rotation of the camshaft 1 the compression plunger 3 enters a suction stroke and said grooves for.

discharge and the outlet bore are interrupted of communication. A pair of the longitudinal grooves 80, 8b for suction on each side respectively communicate to the suction bores 12a, 12b resulting in that the fuel in the oil chamber 13 is suctioned into the pump chamber 16 through passage holes 14a, 14b, circumferential grooves 15a, 15b for suction and suction holes 12a, 12b.

FIG. 3 shows the compression plunger 3 and the distribution plunger 6 on a plunger lift curve a in a relationship of discharging and suction. in the curve a rotational angle a of the cam is given for an abscissa and stroke L of the compression plunger 3 for an ordinate. When the plunger 3 rises by 1 at rotational angle a, the bore 18 is closed and the injection starts and when the plunger reaches 1 at an angle a the bore 18 opens and the injection ends. Accordingly, during the period shown by a solid line A one of the outlet bore 170 com municates to the pump chamber 16 through one of the longitudinal grooves 7a, 7%: for discharge. When the plunger 3 enters a suction stroke at an angle a the suction bores 12a, 12b communicate the longitudinal grooves 8a, 8b for suction. The same condition continues during the period shown by a dotted line B, i.e., the plunger 3 reaches the angle 01,, slightly passing over the lowest position in which the plunger 3 ends its suction stroke. 7

HO. 4 shows a second embodiment of this invention which is adapted for an eight-cylinder engine. The embodiment has two pumps as shown in the first embodiment which are connected in series and in which the camshaft l is provided with cams 2a, 2b each reciprocating the compression piunger whereby the fuei is supplied consecutively to each cylinder similar to the first embodiment. Where the pumps of the first embodiment are connected in series in three or four pairs it is possible to obtain a smali and simple pump adapted for 12 or 16 cylinders.

lt will be apparent that principles of the above described construction and operation may likewise be applied to a multicylinder engine of an odd number. Further by adequate and preferred combination of number of projections on the cam 2, number of the discharge ports 21 and ratio of rotation of the camshaft 1 and the distribution plunger 6, the pump can be adapted for the engine having various numbers of cylinders and various rotational speeds by making minimum change in pans. For example, in the first embodiment for the four cylinder engine the camshaft 1 may be driven at the rotational speed of an engine and the distribution plunger 6 at half the speed of the engine while the number of he suction grooves 8a, 8b, discharge grooves 75, 7b, outiet bores 17a and outlet port 21 etc. may be adapted for the eight cylinder engine and thereby will be obtained a pump for the eight cylinder engine. If the two outlet bores 170 are communicated to an outlet port 21 and these are provided in two in the number there will be obtained a pump for a two cylinder engine which is doubled in the rotational speed of engine. The fuel injection pump according to this invention can moreover fuifill the following conditions desiied as the distribution pump.

1. Complete communication of the oil chamber 13 and the pump chamber 16 respectiveiy by two passage holes 120, 14a or 12b, 14b during the suction stroke of the compres= sion plunger 3 may not effect a negative pressure in the pump chamber 1-5 as encountered in the conventional fuel pumps but enables a stable injection as well as a large bore as desired whereby the problem of shortage of suction amount due to resistance in the suction passage in a high speed operation may be solved. The circumferential groove 7 for discharge and iongitudinal grooves 7a, 7b of the distribution plunger 6 communicate to the oil chamber 13, in sequence, these passages are uniform in the oil feed pressure which avoids the interference of injection between cylinders, irregular injection or other troubles while uniform pressure in the distribution type fuel pump will be ensured.

2. Location of a fuel outlet is not convenient for pipe arrangement in the distribution type fuel pump when it is provided in an engine in place of a conventional row type pumps. This disadvantage has been overcome in this invention by providing outlet ports all on the upper surface of the pump.

Many variations may be effected without departing from he spirit of the invention. It is to be understood that these, together with other variations in details, are anticipated by the appended claims.

I claim:

1. A distribution type fuel injection pump comprising, a casing, a camshaft rotatably mounted in said casing, a pump chamber body in said casing, a compression plunger siidable in said pump chamber body and having the longitudinal axis thereof extending at right angles with respect to the longitudinal axis of said camshaft, a distributor casing, a distributor plunger rotatably mounted in said distributor casing, said distributor plunger being parallel to said camshaft, an oil chamber in said casing between said pump chamber body and said distributor casing, means including passageways in said distributor plunger for interconnecting said pump chamber selectively with said oil chamber and an outlet port, and means including a notch in said compression plunger for controlling the amount of fuel delivered by the fuel injection pump.

2. A distribution type fuel injection pump according to claim 1 wherein the distributor casing forms one wall of the pump chamber and said first named means includes longitudinal grooves in said distributor plunger for connecting the oil chamber with pump chamber on each suction stroke of the compression plunger.

3. A distribution type fuel injection pump according to claim 2 wherein said distribution plunger includes at least one circumferentiai groove and outlet longitudinal grooves communicating with said circumferential groove and at least a pair of outlet ports in said casing, said outlet longitudinal grooves communicating with said outlet ports sequentiaily during sequential compression strokes of said compression plunger. 

1. A distribution type fuel injection pump comprising, a casing, a camshaft rotatably mounted in said casing, a pump chamber body in said casing, a compression plunger slidable in said pump chamber body and having the longitudinal axis thereof extending at right angles with respect to the longitudinal axis of said camshaft, a distributor casing, a distributor plunger rotatably mounted in said distributor casing, said distributor plunger being parallel to said camshaft, an oil chamber in said casing between said pump chamber body and said distributor casing, means including passageways in said distributor plunger for interconnecting said pump chamber selectively with said oil chamber and an outlet port, and means including a notch in said compression plunger for controlling the amount of fuel delivered by the fuel injection pump.
 2. A distribution type fuel injection pump according to claim 1 wherein the distributor casing forms one wall of the pump chamber and said first named means includes longitudinal grooves in said distributor plunger for connecting the oil chamber with pump chamber on each suction stroke of the compression plunger.
 3. A distribution type fuel injection pump according to claim 2 wherein said distribution plunger includes at least one circumferential groove and outlet longitudinal grooves communicating with said circumferential groove and at least a pair of outlet ports in said casing, said outlet longitudinal grooves communicating with said outlet ports sequentially during sequential compression strokes of said compression plunger. 